My present invention relates to an apparatus for the machining of structural shapes and, more particularly, for the drilling of structural shapes having at least two angularly-adjoining flanges and preferably flanges at a right angle to one another. The invention especially relates to an apparatus of the type in which the structural shape is passed through a portal or frame having vertical and horizontal members and in which along at least one of the vertical members and along the horizontal member, respective slides are provided which carry drilling heads or holders for drill bits or spindles for the drilling of holes in respective flanges. The structural shapes in question are also referred to as profiles, usually have two or more angularly adjoining flanges which may be at right angles, and include angles, I-beams, H-beams, T-beams and composites of these shapes.
In steel fabrication, the structural shape must be precisely machined, i.e. drilled to provide holes through which bolts or rivets can be passed to allow an I-beam, H-beam or angle to be connected to another structural shape with or without fish plates or connecting members in erection of steel building structures, bridges, towers and the like. The holes or bores must correspond to a predetermined pattern to allow accurate connection of the structural shape with other members. If, of course, a transverse row of bores is provided, the structural shape may be weakened.
As a practical matter, when structural shapes are used in steel constructions under high load, the bores in the flanges at right angles to one another should be longitudinally offset to minimize the reduction in the load-carrying capacity of the resulting steel or girder, i.e. care should be that bores are not drilled in the various flanges in the same transverse plane.
The offset of bores along the structural shape in the longitudinal direction or along the longitudinal axis thereof is a spacing determined for the later use of the beam or girder and is chosen in accordance with the assembly plan. The distance is variable and can range, usually, to a maximum of several hundred millimeters.
An apparatus for drilling structural shapes is described in EP-B 0 845 317. In this system, the vertical drill unit and the horizontal drill unit located laterally thereof are fixed in position with respect to the longitudinal direction, i.e. the direction of advance of the workpiece through the frame or portal. The workpiece is moved stepwise through the apparatus and is drilled with the horizontal or vertical drilling units to locate the holes at the positions determined by the drilling plan. However, simultaneous drilling by the drilling units of this system is only possible when the bores are to lie in the same cross-sectional plane or are to have a constant axial (longitudinal) offset which is determined by the fixed orientations of the horizontal and vertical drilling units with respect to one another, the longitudinal direction corresponding to the direction of advance of the workpiece.
When the bores in the horizontal and vertical flanges are to have variable longitudinal spacings, the workpiece must always be repositioned to locate the drill bit at the desired point and separately drill the vertical and horizontal flanges. This need to separately drill most of the bores greatly reduces the efficiency and effectiveness of the apparatus and especially when bores of close spacing in the longitudinal direction are required and a number of bores close together in the longitudinal direction are to be made in the various flanges.
It is, therefore, the principal object of the present invention to provide an improved apparatus for the machining of structural shapes, especially the drilling thereof in which bores can be drilled substantially in two mutually perpendicular flanges but with a selected longitudinal offset so as to avoid weakening of the structural shape.
Another object is to provide an apparatus for the purposes described which avoids the drawbacks of the earlier systems.
Still another object of this invention is to provide an improved system for drilling structural shapes such as angles, I-beams and H-beams which has a greater output than has hitherto been the case and can avoid weakening of the structural shape.
A further object of the invention is to provide a more versatile drilling apparatus for structural shapes whereby a plurality of flanges of a structural shape can be simultaneously drilled with bores in a plurality of transverse rows with different longitudinal offsetting without the need to move the structural shape or piece.
These objects are achieved, in accordance with the invention in an apparatus for the machining of structural shapes having two flanges angularly adjoining at a right angle which comprises:
means forming a substantially horizontal transport path for structural shapes to be machined;
a frame along the path having at least one fixed vertical member and at least one fixed horizontal member;
a horizontally displaceable slide on the horizontal member and a vertically displaceable slide on the vertical member; and
respective machining units on the slides for machining respective flanges of a structural shape on the path in the frame, and including at least one drill carrier rotatable on a respective one of the slides about a respective carrier axis transverse to the respective flange, and a holder for a drill bit on the respective carrier radially offset from the carrier axis and rotatable about a drill-bit axis, whereby holes can be drilled by the drill bit at different longitudinal locations along the respective flange upon rotation of the carrier about the carrier axis and at different transverse locations on the respective flange upon displacement of the one of the slides.
According to the invention, the one of the slides and the carrier have respective drives, the apparatus further comprising a controller for the drives for operating the drive of the one of the slides to compensate for a transverse shift of the drill bit upon rotation of the carrier about the carrier axis to obtain a certain longitudinal spacing of the holes.
The carrier can be provided with a plurality of holders for respective drill bits offset radially from the carrier axis and angularly spaced therearound, the drill bits being displaceable selectively into working position for drilling the one of the flanges.
With an apparatus in accordance with the invention, the drilling unit on at last one of the slides is mounted on a rotating carrier with a respective servomotor or positioning drive and the drill bit or holder (spindle) is eccentrically arranged on this carrier, the spindle axis being parallel to the carrier axis. The position of the drill bit in the longitudinal direction can thus be set by the angular position of the carrier while the position in a transverse direction is set by the respective slide so that a compound motion of the slide and carrier can locate the drill bit at any location within range offered by the rotation of the carrier notwithstanding the fact that the slide is guided along a guide which is fixed in the longitudinal direction of the workpiece.
The carriers can be provided on the slides displaceably along both of the vertical limbs or members of the frame or portal and each of these carriers can have a horizontal drilling unit. The slide displaceably horizontally along the traverse of the frame can likewise be equipped with a rotatable carrier and a drill which is radially offset on the carrier form the axis of rotation thereof.
Upon a rotation of the carrier, the drill holder is displaced along a circular path or arc about the axis of rotation of the carrier. The axial displacement offered by the rotation of the carrier will depend on the diameter of this circle which can be several hundred millimeters without difficulty. Within this range the axial position is determined by the angular displacement of the carrier in a stepless manner.
The circular movement of the drill is associated with a transverse displacement which can be compensated by the movement of the respective slide so that the drill bit can be located at exactly the desired position. The carrier drive and the slide drive can be connected to a controller which automatically compensates for the lateral offset by adjusting the respective slider.
The number of drilling heads can be provided eccentrically on the or each carrier and can be selectively brought into working position by rotation of the carrier. A common drive for all of the spindles on a carrier can be provided for the or each carrier.
According to a feature of the invention, the drill carrier is provided with a planetary gear drive or transmission which includes a sun gear, a planet gear with planet gears and an outer gear or ring gear. The drill carrier is connected with the planet carrier and the angular setting of the planet carrier is achieved with a stepping motor connected with the sun gear or the ring tear and which positions the planet carrier and the drill carrier in the desired angular position. The planet gear can be locked by its positioning drive, i.e. the stepping motor, in its working angular position.
It is also advantageous to provide a rotary drive for the spindles on the planet carrier which can rotatably drive the drills via the sun gear. When the planet gear is stationary, the sun gear rotates the planet gears and via the planet gears the spindles of the drilling units. The transmission can include gearing between the planet gears and the spindles to allow these to be rotated at different speeds form one another.